Despite the lack of activity, I haven't given up on this. However, it has come to my attention that I really don't have enough knowledge about how to ensure that this doesn't cause more harm than good. I've made a Tetris for Raspberry Pi that works with HDMI 3D TVs, and that works quite well according to those who have used it, but it seems that it works well for a good reason: both of your eyes are naturally aligned in that case. If I start trying to align two separate displays, it could instead cause eye strain.

A number of things have affected where I was going with this:

1) The release of Raspberry Pi Zero. At this point, there's no real reason to not use that, aside from battery life (but I wasn't sure I was going to end up on batteries anyway). With the Zero, I can wire it to a single larger LCD and use a Google Cardboard to get most of the way there without a huge increase in cost (and probably a decrease in build complexity). I like that.

2) Just having the time to do it... I've got a number of projects in my queue but I haven't had time to look at them over the past year. I'm hoping this changes soon.

3) As mentioned above, a lack of knowledge on how to ensure this doesn't hurt people's eyes.